In fuel injection systems of motor vehicles, it is conceivable for a fuel distributor rail to be used that is made of steel for high-pressure applications. By this means, a pressure resistance for pressures of greater than 15 MPa (150 bar) may be achieved. Such a high-pressure steel rail may be made of soldered rail. In this connection, a steel pipe is used as a base, to which the individual components, in particular, screw caps, bolt-on holders, a high-pressure connection and the interfaces to the injector are soldered. However, this development is associated with high manufacturing costs.
In addition, in the case of such a high-pressure rail, there is the problem of mechanical stresses occurring in the rail. The steel rail may be mounted on a cylinder head, which, as a rule, is made of aluminum. If the engine heats up, then thermal expansion occurs. In this connection, the rail expands, which generates stresses in the rail.
In addition, high manufacturing costs result when such a rail is made up of components. In particular, e.g., a drawn pipe must be cut to length, the ends must be machined, and outlets must be bored. In addition, a wall thickness must be selected to be relatively high, in order that the internal pressure and, additionally, the impeded linear expansion may be absorbed. Thus, the wall thickness may not be oriented to the internal pressure alone, since the wall thickness would then be under-dimensioned for reasons of strength. Cups and holders may be made of finished steel castings or small assemblies or deep-drawn parts. Lathed or deep-drawn parts may be used as top-caps. The high-pressure connections may take the form of lathed parts, for example. However, prior to the final soldering operation, the attachment parts must still be fixed in position with respect to one another. On the whole, such conceivable manufacturing of a rail results in a highly cost-intensive manufacturing process having many working steps.